MILLS AND OTHER BUILDINGS 173 
marked success. We allowed the gas to remain in the 
building one night and day. The next morning we 
found everything had perished, including many mice 
and weevil. ‘The last day or so we have noticed one 
or two weevil, probably some that survived by being 
deeply buried in cracks. We can certainly speak a 
good word for the remedy, and thank you very much 
for your instructions, which has aided us in free- 
ing our mill and warehouse from such troublesome 
pests. 
Repeated applications demonstrated that the remedy 
is one that can be relied upon when properly used. 
An occasional miller, however, may get a bad lot of 
chemicals and can not generate the gas properly. One 
of our Canadian friends wrote recently that he was not 
very successful in his fumigation, stating that the 
cyanide did not work in the acid and water. It was 
apparent to me he had used an old grade of cyanide, 
about 58 per cent. purity, where he should have had 
the chemically pure cyanide, guaranteed 98 to 99 per 
cent. My suspicions were well founded, and a few 
days later, at my suggestion, he tried the pure cyanide 
with good results and wrote me as follows August 15: 
Your letter of July 22 was duly received and care- 
fully noted. About ten days ago we fumigated again 
with the hydrocyanic acid gas, and this time with 
complete success, hardly a bug or grub of any kind 
being left alive. We see anodd one occasionally, both 
moth and weevil, and we expect there will be some 
hatched out from eggs left. We shall fumigate again 
in another month or so if necessary. "The fumigation 
is so simply done, and so deadly, that we have now no 
